U.S. patent application number 17/318585 was filed with the patent office on 2021-11-18 for tire attaching position detection system, tire and sensor unit for tires.
The applicant listed for this patent is TDK Corporation. Invention is credited to Tadao SENRIUCHI, Sadaharu YONEDA.
Application Number | 20210356295 17/318585 |
Document ID | / |
Family ID | 1000005635622 |
Filed Date | 2021-11-18 |
United States Patent
Application |
20210356295 |
Kind Code |
A1 |
SENRIUCHI; Tadao ; et
al. |
November 18, 2021 |
TIRE ATTACHING POSITION DETECTION SYSTEM, TIRE AND SENSOR UNIT FOR
TIRES
Abstract
A tire attaching position detection system is provided which can
suppress influence by an intensity of a reception signal from a
tire. In the system, a sensor unit is mounted on each tire, the
sensor unit has a geomagnetic sensor for acquiring data on
direction change of the tire, a distortion sensor for acquiring
data on number of rotations of the tire and a transmitting part for
transmitting the direction change data and number of rotations data
of the tire. A calculation part of a user terminal judges the
attaching position of each tire based on the direction change data
and the number of rotations data of each tire transmitted from the
transmitting part.
Inventors: |
SENRIUCHI; Tadao; (Tokyo,
JP) ; YONEDA; Sadaharu; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TDK Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
1000005635622 |
Appl. No.: |
17/318585 |
Filed: |
May 12, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01D 5/14 20130101; B60C
19/00 20130101; B62D 15/021 20130101; G01S 19/01 20130101; B60C
2019/004 20130101 |
International
Class: |
G01D 5/14 20060101
G01D005/14; B60C 19/00 20060101 B60C019/00; B62D 15/02 20060101
B62D015/02; G01S 19/01 20060101 G01S019/01 |
Foreign Application Data
Date |
Code |
Application Number |
May 14, 2020 |
JP |
2020-085386 |
Claims
1. A tire attaching position detection system for vehicles,
comprising: a direction change detection means, mounted on each
tire of a vehicle, for acquiring direction change data of each
tire; a means for detecting number of rotations, mounted on each
tire, for acquiring number of rotations data of each tire; a
transmission means, mounted on each tire, for transmitting the
direction change data of each tire and the number of rotations data
of each tire; and a position judging means for judging the
attaching position of each tire in the vehicle based on the
direction change data and the number of rotations data transmitted
from the transmission means of each tire.
2. The tire attaching position detection system according to claim
1, wherein the position judging means judges some tires as the
front wheels in at least any one of the following cases (1) to (7)
and judges each tire as the right wheel or the left wheel according
to large or small of the number of rotations during period of
turning of the vehicle: (1) when the direction changes of the above
some tires are detected before the direction changes of the other
tires at the time when the vehicle changes its traveling direction;
(2) when the direction changes of the above some tires are detected
and the direction changes of the other tires are not detected; (3)
when it is detected that the direction changes of the above some
tires are larger than the direction changes of the other tires at
the time of transition from straight traveling to curving; (4) when
the direction changes of the above some tires are linked with
turning of a steering wheel of the vehicle and the direction
changes of the other tires are not linked with the turning of the
steering wheel; (5) when the direction changes of the above some
tires are smaller than the direction changes of the other tires
between the time of the start of curving of the vehicle and the
time of the end of curving; (6) when the direction changes of the
above some tires are smaller than the direction changes of the
other tires between the time when the direction changes of at least
the above some tires are detected after same direction state of all
the tires and the time when all the tires become same direction
state again after that; and (7) when the direction changes of the
above some tires coincide with the change of the traveling
direction instructed by the turning of the steering wheel of the
vehicle and the direction changes of the other tires do not
coincide with the change of the traveling direction.
3. A tire attaching position detection system for vehicles,
comprising: a direction change detection means, mounted on each
tire of a vehicle, for acquiring direction change data of each
tire; a transmission means, mounted on each tire, for transmitting
the direction change data of each tire; and a position judging
means for judging whether each tire is a front wheel or rear wheel
based on the direction change data transmitted from the
transmission means of each tire, wherein at a vehicle speed lower
than a predetermined speed, the position judging means judges some
tires as the front wheels in at least any one of the following
cases (1) to (7): (1) when the direction changes of the above some
tires are detected before the direction changes of the other tires
at the time when the vehicle changes its traveling direction; (2)
when the direction changes of the above some tires are detected and
the direction changes of the other tires are not detected; (3) when
it is detected that the direction changes of the above some tires
are larger than the direction changes of the other tires at the
time of transition from straight traveling to curving; (4) when the
direction changes of the above some tires are linked with turning
of a steering wheel of the vehicle and the direction changes of the
other tires are not linked with the turning of the steering wheel;
(5) when the direction changes of the above some tires are smaller
than the direction changes of the other tires between the time of
the start of curving of the vehicle and the time of the end of
curving; (6) when the direction changes of the above some tires are
smaller than the direction changes of the other tires between the
time when the direction changes of at least the above some tires
are detected after same direction state of all the tires and the
time when all the tires become same direction state again after
that; and (7) when the direction changes of the above some tires
coincide with the change of the traveling direction instructed by
the turning of the steering wheel of the vehicle and the direction
changes of the other tires do not coincide with the change of the
traveling direction.
4. The tire attaching position detection system according to claim
1, wherein the direction change detection means includes a magnetic
sensor capable of detecting terrestrial magnetism.
5. The tire attaching position detection system according to claim
4, wherein the magnetic sensor is of a three-axis type, the first
axis is parallel to a rotation axis of a tire on which the magnetic
sensor is mounted, the second axis is parallel to a rotation
tangent direction of a magnetic sensor mounting part, and the third
axis is vertical to the first axis and the second axis.
6. The tire attaching position detection system according to claim
5, comprising first and second ground detection sensors mounted on
each tire, wherein the first ground detection sensor is located in
the vicinity of the magnetic sensor in the circumferential
direction of the tire, the second ground detection sensor is
located on a side opposite to the first ground detection sensor
with the rotation center of the tire between them, and the position
judging means judges whether the magnetic sensor is located on the
front part or rear part of the tire from the detection signals of
the first and second ground detection sensors, so that the position
judging means detects the direction of the tire.
7. A tire attaching position detection system for vehicles,
comprising: a means for detecting number of rotations, mounted on
each tire, for acquiring number of rotations data of each tire; a
transmission means, mounted on each tire, for transmitting the
number of rotations data of each tire, and a position judging means
for judging whether each tire is a right wheel or left wheel based
on the number of rotations data transmitted from the transmission
means of each tire, wherein the position judging means judges
whether each tire is a right wheel or left wheel according to large
or small of the number of rotations during period of turning of the
vehicle.
8. The tire attaching position detection system according to claim
1, wherein the means for detecting number of rotations includes a
ground detection sensor.
9. (canceled)
10. The tire attaching position detection system according to claim
1, comprises a receiver of a satellite positioning system and can
judge turning direction of the vehicle from a reception signal of
the receiver.
11. The tire attaching position detection system according to claim
1, comprising an input means which enables a user to input turning
direction of the vehicle, and recognize the turning direction of
the vehicle from an input of the turning direction into the input
means.
12. The tire attaching position detection system according to claim
1, comprising an input means which enables a user to instruct a
start of detection of a tire attaching position and a display means
for displaying whether the tire attaching position is detected or
not.
13. The tire attaching position detection system according to claim
1, comprising a state acquisition means, mounted on each tire, for
acquiring data on a state of each tire, wherein the transmission
means transmits the data on the state of each tire.
14. (canceled)
15. (canceled)
16. (canceled)
17. The tire attaching position detection system according to claim
3, wherein the direction change detection means includes a magnetic
sensor capable of detecting terrestrial magnetism.
18. The tire attaching position detection system according to claim
17, wherein the magnetic sensor is of a three-axis type, the first
axis is parallel to a rotation axis of a tire on which the magnetic
sensor is mounted, the second axis is parallel to a rotation
tangent direction of a magnetic sensor mounting part, and the third
axis is vertical to the first axis and the second axis.
19. The tire attaching position detection system according to claim
18, comprising first and second ground detection sensors mounted on
each tire, wherein the first ground detection sensor is located in
the vicinity of the magnetic sensor in the circumferential
direction of the tire, the second ground detection sensor is
located on a side opposite to the first ground detection sensor
with the rotation center of the tire between them, and the position
judging means judges whether the magnetic sensor is located on the
front part or rear part of the tire from the detection signals of
the first and second ground detection sensors, so that the position
judging means detects the direction of the tire.
20. The tire attaching position detection system according to claim
7, wherein the means for detecting number of rotations includes a
ground detection sensor.
21. (canceled)
22. The tire attaching position detection system according to claim
3, comprises a receiver of a satellite positioning system and can
judge turning direction of the vehicle from a reception signal of
the receiver.
23. The tire attaching position detection system according to claim
7, comprises a receiver of a satellite positioning system and can
judge turning direction of the vehicle from a reception signal of
the receiver.
24. The tire attaching position detection system according to claim
3, comprising an input means which enables a user to input turning
direction of the vehicle, and recognize the turning direction of
the vehicle from an input of the turning direction into the input
means.
25. The tire attaching position detection system according to claim
7, comprising an input means which enables a user to input turning
direction of the vehicle, and recognize the turning direction of
the vehicle from an input of the turning direction into the input
means.
26. The tire attaching position detection system according to claim
3, comprising an input means which enables a user to instruct a
start of detection of a tire attaching position and a display means
for displaying whether the tire attaching position is detected or
not.
27. The tire attaching position detection system according to claim
7, comprising an input means which enables a user to instruct a
start of detection of a tire attaching position and a display means
for displaying whether the tire attaching position is detected or
not.
28. The tire attaching position detection system according to claim
3, comprising a state acquisition means, mounted on each tire, for
acquiring data on a state of each tire, wherein the transmission
means transmits the data on the state of each tire.
29. The tire attaching position detection system according to claim
7, comprising a state acquisition means, mounted on each tire, for
acquiring data on a state of each tire, wherein the transmission
means transmits the data on the state of each tire.
Description
TECHNICAL FIELD
[0001] The present invention relates to a tire attaching position
detection system for vehicles, a tire and a sensor unit for
tires.
BACKGROUND ART
[0002] As a system for monitoring an air pressure of each tire
attached to a vehicle, there is known TPMS (Tire Pressure
Monitoring System). In the TPMS, an air pressure sensor unit
mounted on each tire transmits a detection result together with
tire ID to a receiver on a car body side by wireless communication.
A computer on the car body side displays a warning on a screen etc.
for a driver when a content received by the receiver indicates a
reduction in the air pressure of the tire. To specify which tire
the reduction in air pressure occurs, the computer on the car body
side must recognize the position of each tire, that is, which tire
of each ID is attached to the front left, front right, rear left or
rear right wheel.
[0003] Patent Document 1 below discloses a tire pressure monitoring
system. This system has air pressure sensor units equipped with a
wireless transmitter, each provided on each tire, and a controller
having a receiver. The receiver is installed in such a manner that
its distance from each air pressure sensor unit is different. Each
air pressure sensor unit transmits the tire ID and the detection
result of the air pressure by wireless to the receiver. The
controller compares intensities of reception signals from the air
pressure sensor units in the receiver to specify the attaching
position of each tire.
PRIOR ART DOCUMENT
Patent Document
[0004] [Patent Document 1] Japanese Laid-Open Patent Publication
No. 2008-049875
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0005] In the system of Patent Document 1, it is assumed that, in
fact, the intensity of the reception signal of the receiver depends
on not only a distance from each air pressure sensor unit but also
the intensity of the output signal of the transmitter of each air
pressure sensor unit and existence or nonexistence of a shield
between the receiver and each air pressure sensor unit. Therefore,
it is difficult in fact to specify the tire attaching position from
the intensity of the reception signal.
[0006] When the tire ID and the detection result of the air
pressure are merely transmitted from the tire by wireless as in
Patent Document 1, the tire attaching position can be specified
only by the intensity of the reception signal on the receiving
side. It is difficult in fact to specify the tire attaching
position by the intensity of the reception signal as described
above. That is, in the tire of Patent Document 1, it is difficult
in fact for the receiving side to recognize the tire attaching
position.
[0007] It is a first object of the present invention to provide a
tire attaching position detection system which is capable of
suppressing influence by an intensity of a reception signal from
the tire side.
[0008] It is a second object of the present invention to provide a
tire which is capable of suppressing influence by an intensity of a
reception signal on a receiving side when the receiving side is
caused to recognize the tire attaching position.
[0009] It is a third object of the present invention to provide a
sensor unit for tires which is capable of suppressing influence by
an intensity of a reception signal on a receiving side when the
receiving side is caused to recognize the tire attaching
position.
Means for Solving the Problem
[0010] A first aspect of the present invention relates to a tire
attaching position detection system for vehicles. The tire
attaching position detection system includes:
[0011] a direction change detection means, mounted on each tire of
a vehicle, for acquiring direction change data of each tire;
[0012] a means for detecting number of rotations, mounted on each
tire, for acquiring number of rotations data of each tire;
[0013] a transmission means, mounted on each tire, for transmitting
the direction change data of each tire and the number of rotations
data of each tire; and
[0014] a position judging means for judging the attaching position
of each tire in the vehicle based on the direction change data and
the number of rotations data transmitted from the transmission
means of each tire.
[0015] The position judging means may judge some tires as the front
wheels in at least any one of the following cases (1) to (7) and
judges each tire as the right wheel or the left wheel according to
large or small of the number of rotations during period of turning
of the vehicle: [0016] (1) when the direction changes of the above
some tires are detected before the direction changes of the other
tires at the time when the vehicle changes its traveling direction;
[0017] (2) when the direction changes of the above some tires are
detected and the direction changes of the other tires are not
detected; [0018] (3) when it is detected that the direction changes
of the above some tires are larger than the direction changes of
the other tires at the time of transition from straight traveling
to curving; [0019] (4) when the direction changes of the above some
tires are linked with turning of a steering wheel of the vehicle
and the direction changes of the other tires are not linked with
the turning of the steering wheel; [0020] (5) when the direction
changes of the above some tires are smaller than the direction
changes of the other tires between the time of the start of curving
of the vehicle and the time of the end of curving; [0021] (6) when
the direction changes of the above some tires are smaller than the
direction changes of the other tires between the time when the
direction changes of at least the above some tires are detected
after same direction state of all the tires and the time when all
the tires become same direction state again after that; and [0022]
(7) when the direction changes of the above some tires coincide
with the change of the traveling direction instructed by the
turning of the steering wheel of the vehicle and the direction
changes of the other tires do not coincide with the change of the
traveling direction.
[0023] A second aspect of the present invention relates to a tire
attaching position detection system for vehicles. The tire
attaching position detection system includes:
[0024] a direction change detection means, mounted on each tire of
a vehicle, for acquiring direction change data of each tire;
[0025] a transmission means, mounted on each tire, for transmitting
the direction change data of each tire; and
[0026] a position judging means for judging whether each tire is a
front wheel or rear wheel based on the direction change data
transmitted from the transmission means of each tire, wherein
[0027] at a vehicle speed lower than a predetermined speed, the
position judging means judges some tires as the front wheels in at
least any one of the following cases (1) to (7): [0028] (1) when
the direction changes of the above some tires are detected before
the direction changes of the other tires at the time when the
vehicle changes its traveling direction; [0029] (2) when the
direction changes of the above some tires are detected and the
direction changes of the other tires are not detected; [0030] (3)
when it is detected that the direction changes of the above some
tires are larger than the direction changes of the other tires at
the time of transition from straight traveling to curving; [0031]
(4) when the direction changes of the above some tires are linked
with turning of a steering wheel of the vehicle and the direction
changes of the other tires are not linked with the turning of the
steering wheel; [0032] (5) when the direction changes of the above
some tires are smaller than the direction changes of the other
tires between the time of the start of curving of the vehicle and
the time of the end of curving; [0033] (6) when the direction
changes of the above some tires are smaller than the direction
changes of the other tires between the time when the direction
changes of at least the above some tires are detected after same
direction state of all the tires and the time when all the tires
become same direction state again after that; and [0034] (7) when
the direction changes of the above some tires coincide with the
change of the traveling direction instructed by the turning of the
steering wheel of the vehicle and the direction changes of the
other tires do not coincide with the change of the traveling
direction.
[0035] The direction change detection means may include a magnetic
sensor capable of detecting terrestrial magnetism.
[0036] The magnetic sensor may be of a three-axis type, the first
axis is parallel to a rotation axis of a tire on which the magnetic
sensor is mounted, the second axis is parallel to a rotation
tangent direction of a magnetic sensor mounting part, and the third
axis is vertical to the first axis and the second axis.
[0037] The tire attaching position detection system may include
first and second ground detection sensors mounted on each tire,
wherein the first ground detection sensor is located in the
vicinity of the magnetic sensor in the circumferential direction of
the tire, the second ground detection sensor is located on aside
opposite to the first ground detection sensor with the rotation
center of the tire between them, and the position judging means
judges whether the magnetic sensor is located on the front part or
rear part of the tire from the detection signals of the first and
second ground detection sensors, so that the position judging means
detects the direction of the tire.
[0038] A third aspect of the present invention relates to a tire
attaching position detection system for vehicles. The tire
attaching position detection system includes:
[0039] a means for detecting number of rotations, mounted on each
tire, for acquiring number of rotations data of each tire;
[0040] a transmission means, mounted on each tire, for transmitting
the number of rotations data of each tire, and
[0041] a position judging means for judging whether each tire is a
right wheel or left wheel based on the number of rotations data
transmitted from the transmission means of each tire, wherein the
position judging means judges whether each tire is a right wheel or
left wheel according to large or small of the number of rotations
during period of turning of the vehicle.
[0042] The means for detecting number of rotations may include a
ground detection sensor.
[0043] The ground detection sensor may be a distortion sensor or
acceleration sensor.
[0044] The tire attaching position detection system may include a
receiver of a satellite positioning system and can judge turning
direction of the vehicle from a reception signal of the
receiver.
[0045] The tire attaching position detection system may includes an
input means which enables a user to input turning direction of the
vehicle, and recognize the turning direction of the vehicle from an
input of the turning direction into the input means.
[0046] The tire attaching position detection system may includes an
input means which enables a user to instruct a start of detection
of a tire attaching position and a display means for displaying
whether the tire attaching position is detected or not.
[0047] The tire attaching position detection system may includes a
state acquisition means, mounted on each tire, for acquiring data
on a state of each tire, wherein the transmission means transmits
the data on the state of each tire.
[0048] A forth aspect of the present invention relates to a tire.
The tire includes a magnetic sensor capable of detecting
terrestrial magnetism and a transmitting part capable of
transmitting an output signal of the magnetic sensor to outside by
wireless.
[0049] The tire may includes a ground detection sensor, wherein the
transmitting part can transmit an output signal of the ground
detection sensor to the outside by wireless.
[0050] A fifth aspect of the present invention relates to a sensor
unit for tires. The sensor unit includes a magnetic sensor capable
of detecting terrestrial magnetism and a transmitting part capable
of transmitting an output signal of the magnetic sensor to outside
by wireless.
[0051] It is to be noted that any arbitrary combination of the
above-described structural components as well as the expressions
according to the present invention changed among a system and so
forth are all effective as and encompassed by the present
aspects.
Effect of the Invention
[0052] According to the first to third aspects of the present
invention, there can be provided a tire attaching position
detection system which is capable of suppressing influence by an
intensity of a reception signal from the tire side.
[0053] According to the fourth aspect of the present invention,
there can be provided a tire which is capable of suppressing
influence by an intensity of a reception signal on a receiving side
when the receiving side is caused to recognize the tire attaching
position.
[0054] According to the fifth aspect of the present invention,
there can be provided a sensor unit for tires which is capable of
suppressing influence by an intensity of a reception signal on the
receiving side when the receiving side is caused to recognize the
tire attaching position.
BRIEF DESCRIPTION OF THE DRAWINGS
[0055] FIG. 1 is a schematic plan view of a tire attaching position
detection system 1 according to an embodiment of the present
invention.
[0056] FIG. 2 is a functional block diagram of the tire attaching
position detection system 1.
[0057] FIG. 3 is a schematic plan view showing posture changes of
tires 3 and a car body 5 when a front-wheel steering vehicle 2
travels straight, curves and travels straight sequentially.
[0058] FIG. 4 is a schematic plan view showing posture changes of
tires 3 and a car body 5 when a four-wheel steering vehicle 2
travels straight, curves and travels straight sequentially.
[0059] FIG. 5 is a schematic plan view showing a difference in
turning radius between inner wheels and outer wheels when the
vehicle 2 curves.
[0060] FIG. 6 is a sectional view showing the position of the
sensor unit 4 of the tire attaching position detection system
1.
[0061] FIG. 7 is a schematic sectional side view showing a ground
contact state between a road surface 7 and a part of an outer tire
surface at which right behind of a mounting part of the sensor unit
4 is positioned.
[0062] FIG. 8 is a diagram showing an example of a waveform of a
sensing signal of a distortion sensor 11 of the sensor unit 4.
[0063] FIG. 9 is a schematic perspective view showing directions of
x, y and z axes which are detection axes of a geomagnetic sensor 12
of the sensor unit 4.
[0064] FIG. 10 is a schematic plan view showing an angle .theta.
formed by a traveling direction of the tire 3 with respect to
north-south direction.
[0065] FIG. 11 is a graph showing a relationship between a
detection result of the geomagnetic sensor 12 and the angle
.theta..
[0066] FIG. 12 is a flowchart showing a flow of a tire attaching
position detecting method which can be applied to a front-wheel
steering vehicle 2.
[0067] FIG. 13 is a flowchart showing a flow of a tire attaching
position detecting method which can be applied to front-wheel
steering and four-wheel steering vehicles 2.
[0068] FIG. 14 is a schematic side view showing that two distortion
sensors 11a and 11b are arranged at an interval of 180.degree. in a
circumferential direction of the tire 3 and the distortion sensor
11b is arranged at the same position as a geomagnetic sensor 12 in
the circumferential direction of the tire 3.
[0069] FIG. 15 is a graph showing a relationship between the
detection result of the geomagnetic sensor 12 and the angle .theta.
in view of whether the geomagnetic sensor 12 is located on the
front half or rear half of the tire 3 in the configuration of FIG.
14.
EMBODIMENT FOR CARRYING OUT THE INVENTION
[0070] Preferred embodiments of the present invention will now be
described in detail with reference to the drawings. The same or
equivalent constituent parts, members, etc., shown in the drawings
are designated by the same reference numerals and will not be
repeatedly described as appropriate. The embodiments are not
intended to limit the invention but are mere exemplifications, and
all features or combinations thereof described in the embodiments
do not necessarily represent the intrinsic natures of the
invention.
[0071] This embodiment relates to a tire attaching position
detection system 1 for vehicles, a tire 3 and a tire sensor unit 4.
The front, rear, right and left directions crossing each other of a
vehicle 2 are defined by FIG. 1. The vehicle 2 has a car body 5 and
four tires 3 attached to the car body 5. The tires 3 consist of a
front left wheel 3a, a front right wheel 3b, a rear left wheel 3c
and a rear right wheel 3d. When it is necessary to explain by
specifying one of them, expressions "front left wheel 3a", "front
right wheel 3b", "rear left wheel 3c" and "rear right wheel 3d" are
used. In other cases, an expression "tire 3" is used. The vehicle 2
is a front-wheel steering (double-wheel steering) vehicle or a
four-wheel steering vehicle.
[0072] The tire attaching position detection system 1 includes
sensor units 4 mounted on the respective tires 3 respectively and a
user terminal 20. In the tire attaching position detection system
1, the user terminal 20 communicates with the sensor unit 4 of each
tire 3 to detect the attaching position of each tire 3, that is,
whether the tire 3 is a front left wheel, front right wheel, rear
left wheel or rear right wheel. The detection of the attaching
position of each tire 3 is carried out after exchange of the tire 3
or after rotation of the tire 3 in the vehicle 2.
[0073] As shown in FIG. 2, the sensor unit 4 has a distortion
sensor 11 as a means for detecting number of rotations (in other
words a rotation speed detecting means), a geomagnetic sensor 12 as
a direction change detection means, an air pressure sensor 13 as a
state acquisition means and a transmitting part 15 as a
transmission means.
[0074] The distortion sensor 11 is a thin-film piezoelectric
element chip having an electrode on both sides of a piezoelectric
thin film (thin-film PZT) and mounted on an unshown flexible
substrate. The distortion sensor 11 acquires data on the number of
rotations of the tire 3. The geomagnetic sensor 12 is an example of
a magnetic sensor which can detect terrestrial magnetism and
acquires data on the direction change of the tire 3. The air
pressure sensor 13 acquires air pressure data which is an example
of the state data of the tire 3.
[0075] The transmitting part 15 is a wireless communication module
for short-range wireless communication such as Bluetooth
(registered trademark). The transmitting part 15 may include a
signal processing part for carrying out signal processing such as
noise removal, amplifying or analog-digital conversion. The
transmitting part 15 transmits the number of rotations data
acquired by the distortion sensor 11, the direction change data
acquired by the geomagnetic sensor 12 and the air pressure data
acquired by the air pressure sensor 15 to the receiving part 21 of
the user terminal 20. The transmitting part 15 may transmit the ID
of the tire 3 to the receiving part 21.
[0076] The user terminal 20 may be a computer (on-vehicle computer)
which constitutes a car navigation system of the vehicle 2 or a
portable terminal such as smart phone or tablet terminal. The user
terminal 20 has the receiving part 21, a GPS (Global Positioning
System) receiver 22, a calculation part 23, a display part 24 as a
display means and an input part 25 as an input means.
[0077] The receiving part 21 is a wireless communication module for
short-range wireless communication such as Bluetooth (registered
trademark). The GPS receiver 22 is an example of the receiver of a
satellite positioning system. The calculation part 23 includes a
microcontroller which can carry out various arithmetic processing
required for the detection of the attaching position of the tire 3.
The display part 24 reports various information to a user by screen
display. The input part 25 includes buttons etc. which accept
various inputs from a user. When the display part 24 is a touch
panel, the touch panel may be used as the input part 25. The user
can instruct the start of the detection of the attaching position
of each tire 3 with the input part 25.
[0078] FIG. 3 is a schematic plan view showing posture changes of
the tires 3 and the car body 5 when a front-wheel steering vehicle
2 travels straight, curves and travels straight sequentially. As
shown in (A) of FIG. 3, when the vehicle 2 travels straight, the
directions of all the tires 3 are the same (aligned). When the
vehicle 2 changes from straight traveling to curving as shown in
(B) of FIG. 3, the front wheels (front left wheel 3a and front
right wheel 3b) first turn in the traveling direction. Thereafter,
along with the curving of the vehicle 2, the rear wheels (rear left
wheel 3c and rear right wheel 3d) turn after the front wheels as
shown in (C) of FIG. 3. Then, when the vehicle 2 returns to
straight traveling as shown in (D) of FIG. 3, the directions of all
the tires 3 become the same. Between at the time of the start of
curving shown in (B) of FIG. 3 and at the time of the end of
curving shown in (D) FIG. 3, an amount of direction change of each
of the front wheels is smaller than an amount of direction change
of each of the rear wheels.
[0079] FIG. 4 is a schematic plan view showing posture changes of
the tires 3 and the car body 5 when a four wheel-steering vehicle 2
travels straight, curves and travels straight sequentially. As
shown in (A) of FIG. 4, when the vehicle 2 travels straight, the
directions of all the tires 3 are the same. When the vehicle 2
changes from straight traveling to curving as shown in (B) of FIG.
4, the front wheels and the rear wheels change in direction in an
opposite phase. That is, the front wheels turn in the traveling
direction whereas the rear wheels turn in a direction opposite to
the traveling direction. The vehicle 2 curves to become a state
shown in (C) of FIG. 4 and then returns to straight traveling as
shown in (D) of FIG. 4, the directions of all the tires 3 become
the same. Between at the time of the start of curving shown in (B)
of FIG. 4 and at the time of the end of curving shown in (D) of
FIG. 4, the amount of direction change of each of the front wheels
is smaller than the amount of direction change of each of the rear
wheels.
[0080] In addition, in the case of front-wheel steering, the
direction changes of the front wheels are linked with the turning
of the steering wheel of the vehicle 2 whereas the direction
changes of the rear wheels are not linked with the turning of the
steering wheel. Further, the direction changes of the front wheels
coincide with the change of the traveling direction instructed by
the turning of the steering wheel of the vehicle 2 whereas the
direction changes of the rear wheels do not coincide with the
change of the traveling direction instructed by the turning of the
steering wheel (the directions of the rear wheels do not change
only by the turning of the steering wheel). In the case of
four-wheeled steering, at a vehicle speed lower than a
predetermined speed at which the front wheels and the rear wheels
change their directions in an opposite phase, the direction changes
of the front wheels coincide with the change of the traveling
direction instructed by the turning of the steering wheel of the
vehicle 2 whereas the direction changes of the rear wheels do not
coincide with the change of the traveling direction instructed by
the turning of the steering wheel (opposite to the change of the
traveling direction).
[0081] In view of these, the calculation part 23 of the user
terminal 20 can judge some tires 3 as the front wheels and the
other tires 3 as the rear wheels based on data on the direction
change of each tire 3 transmitted from the transmitting part 15 in
at least any one of the following cases: [0082] (1) when the
direction changes of the above some tires 3 are detected before the
direction changes of the other tires 3 at the time when the vehicle
2 changes its traveling direction; [0083] (2) when the direction
changes of the above some tires 3 are detected and the direction
changes of the other tires 3 are not detected; [0084] (3) when it
is detected that the direction changes of the above some tires 3
are larger than the direction changes of the other tires 3 at the
time of transition from straight traveling to curving; [0085] (4)
when the direction changes of the above some tires 3 are linked
with the turning of the steering wheel of the vehicle 2 and the
direction changes of the other tires 3 are not linked with the
turning of the steering wheel; [0086] (5) when the direction
changes of the above some tires 3 are smaller than the direction
changes of the other tires 3 between the time of the start of
curving of the vehicle 2 and the time of the end of curving; [0087]
(6) when the direction changes of the above some tires 3 are
smaller than the direction changes of the other tires 3 between the
time when the direction changes of at least the above some tires 3
are detected after same direction state of all the tires 3 and the
time when all the tires 3 become same direction state again after
that; and [0088] (7) when the direction changes of the above some
tires 3 coincide with the change of the traveling direction
instructed by the turning of the steering wheel of the vehicle 2
and the direction changes of the other tires 3 do not coincide with
the change of the traveling direction.
[0089] The above (1) to (4) are judging conditions in the case of a
front-wheel steering vehicle 2. The above (5) to (7) are judging
conditions common to front-wheel steering and four-wheel
steering.
[0090] FIG. 5 is a schematic plan view showing the difference in
turning radius between the inner wheels and the outer wheels when
the vehicle 2 curves. As obvious from FIG. 5, when the vehicle 2
turns to the right, the right wheels (front right wheel 3b and rear
right wheel 3d) which are the inner wheels have the smaller
curvature radius of the trajectory and a shorter moving length than
the left wheels (front left wheel 3a and rear left wheel 3c) which
are the outer wheels. Based on data of the number of rotations of
each tire 3 transmitted from the transmitting part 15, the
calculation part 23 of the user terminal 20 can derive a long and
short moving length of each tire 3 during a period of turning
(curving) from large and small number of rotations of each tire 3
along with the turning (curving) of the vehicle 2. Tires 3 having
higher number of rotations by turning are tires 3 having a longer
moving length by the turning, and the calculation part 23 can judge
these tires 3 as the outer wheels at the time of turning. Tires 3
having a lower number of rotations by the turning are tires 3
having a shorter moving length by the turning, and the calculation
part 23 can judge these tires 3 as the inner wheels at the time of
turning.
[0091] As shown in FIG. 6, the sensor unit 4 is mounted on the
center part in the lateral direction of the inner wall of the tire
3. The distortion sensor 11 of the sensor unit 4 obtains a sensing
signal whose level is changed before and after the ground contact
state shown in FIG. 7 by the rotation of the tire 3. One example of
the waveform of the sensing signal is shown in FIG. 8. As shown in
FIG. 8, the waveform of the sensing signal takes a minimum value
every time the ground contact state shown in FIG. 7 is obtained
during the rotation of the tire 3. The tire 3 makes one revolution
during a period from a certain minimum value to the next minimum
value. Therefore, the number of rotations of the tire 3 during a
desired period can be specified from the sensing signal. That is,
the sensing signal is an example of data of number of rotations
from which the number of rotations of the tire 3 can be
specified.
[0092] FIG. 9 is a schematic perspective view showing the
directions of X, Y and Z axes which are the detection axes of the
geomagnetic sensor 12 of the sensor unit 4. The geomagnetic sensor
12 is of a three-axis type. The X axis as the first axis is
parallel to the rotation axis of the tire 3 (parallel to the width
direction of the tire 3) on which the geomagnetic sensor 12 is
mounted. The Z axis which is the second axis is vertical to the X
axis and parallel to the rotation tangential direction of a
geomagnetic sensor 12 mounting part. The Y axis which is the third
axis is vertical to the X axis and the Z axis. The Y axis is a line
connecting the geomagnetic sensor 12 and the center of the tire
3.
[0093] The measurement values of the axes of the geomagnetic sensor
12 are defined as follows.
X axis measurement value . . . mx Y axis measurement value . . . my
Z axis measurement value . . . mz
[0094] The angle .theta. formed by the traveling direction of the
tire 3 with respect to the north-south direction is defined as
shown in FIG. 10. The graph of FIG. 11 shows results obtained by
plotting the formula 1 on coordinates while the angle .theta. is
changed.
(mx, {square root over (my.sup.2+mz.sup.2)}) [formula 1]
The coordinate values shown in the formula 1 are determined by the
direction of the tire 3 regardless the rotation of the tire 3. In
FIG. 11, the measurement result of the geomagnetic sensor 12 in the
state of FIG. 10 and the origin of the coordinates are connected by
a line segment. The direction of this line segment is the detection
result of the traveling direction of the tire 3. The traveling
direction of the tire 3 and its change can be detected from the
measurement result of the geomagnetic sensor 12.
[0095] FIG. 12 and FIG. 13 show examples of the procedure of
detecting the attaching position of each tire 3 in the tire
attaching position detection system 1. The flowcharts of FIG. 12
and FIG. 13 show a flow of processing when the calculation part 23
runs a tire attaching position detection program. The start of
these flowcharts is triggered, for example, when the input part 25
accepts an instruction to start the detection of the tire attaching
position from a user.
[0096] FIG. 12 is a flowchart showing a flow of a tire attaching
position detecting method which can be applied to a front-wheel
steering vehicle 2. When the calculation part 23 detects the
direction changes of some tires 3 based on data on the direction
change of each tire 3 transmitted from the transmitting part 15
(yes of S1), it judges the tires 3 whose direction has been changed
as the front wheels (S2). Prior to step S1, the calculation part 23
may instruct a user to turn the steering wheel by screen display
with the display part 24 or sound generated from unshown sound
output means. In this case, the turning direction of the steering
wheel may be input (selected) from the input part 25.
[0097] The calculation part 23 starts to measure the number of
rotations (rotation speed) of each tire 3 based on the data of
number of rotations transmitted from the transmitting part 15 (S3).
When the calculation part 23 detects the difference in the number
of rotations among the four tires 3 (yes of S4), it stops measuring
the number of rotations of each tire 3 (S5). With respect to the
front and rear wheels, the calculation part 23 judges some tires 3
having higher number of rotations as the outer wheels and the other
tires 3 having lower number of rotations as the inner wheels (S6).
When the vehicle 2 turns to the right in the process of carrying
out steps S1 to S5, the calculation part 23 judges the inner wheels
as the right wheels and the outer wheels as the left wheels, and
when the vehicle 2 turns to the left, the calculation part 23
judges the inner wheels as the left wheels and the outer wheels as
the right wheels (S7). The calculation part 23 reports whether
judgment has been made normally or not to the user by screen
display with the display part 24 or by sound.
[0098] FIG. 13 is a flowchart showing a flow of a tire attaching
position detecting method which can be applied to front-wheel
steering and four-wheel steering vehicles 2. When the calculation
part 23 detects that the directions of the tires 3 have been
changed (two tires 3 and the other two tires 3 are different in
direction) based on data on the direction change of each tire 3
transmitted from the transmitting part 15 (yes of S11) and the
vehicle 2 has a low speed (yes of S12), the calculation part 23
starts to measure the number of rotations of each tire 3 based on
the data of number of rotations transmitted from the transmitting
part 15 (S13). When the calculation part 23 detects that the
directions of two tires 3 differ from the directions of the other
two tires 3, it can judge the start of turning. The low speed is
lower than a predetermined speed that is a vehicle speed at which
the front wheels and rear wheels of the four-wheeled steering
vehicle 2 change in direction in an opposite phase.
[0099] The calculation part 23 stops measuring the number of
rotations of each tire 3 (S15) when the directions of all the tires
3 become the same (yes of S14), that is, the vehicle 2 ends turning
and returns to straight traveling (the direction change of the car
body 5 ends). The calculation part 23 judges two tires 3 whose
direction changes are small from the time of step S11 as the front
wheels (S16). The calculation part 23 judges some tires having
higher number of rotations as the outer wheels and the other tires
3 having a lower number of rotations as the inner wheels (S17).
When the vehicle 2 turns to the right in the process of carrying
out steps S11 to S15, the calculation part 23 judges the inner
wheels as the right wheels and the outer wheels as the left wheels,
and when the vehicle 2 turns to the left (S18) it judges the inner
wheels as the left wheels and the outer wheels as the right wheels.
The calculation part 23 reports whether judgement has been made
normally or not to the user by screen display with the display part
24 or by sound.
[0100] The calculation part 23 can detect the turning direction of
the vehicle 2 from the reception signal of the GPS receiver 22 in
step S7 in FIG. 12 and step S18 in FIG. 13. Or when the user inputs
the rotation direction of the steering wheel from the input part 24
in advance, the calculation part 23 may judge that the vehicle 2
turns in a direction shown by the rotation direction. Or the
calculation part 23 may derive the turning direction from the
difference in direction between the rear wheels and the front
wheels based on data on the direction change of each tire 3
transmitted from the transmitting part 15. Or unshown steering
wheel rotation position detection means may be provided, so that
the calculation part 23 derives the turning direction from the
rotation direction of the steering wheel.
[0101] The flowchart of FIG. 12 can be applied regardless of the
forward movement or backward movement of the vehicle 2. The
flowchart of FIG. 13 is based on the supposition of the forward
movement of the vehicle 2. In this point, prior to step S11, the
calculation part 23 may instruct the user to drive the vehicle
forward by screen display with the display part 24 or by sound. Or
the calculation part 23 may reverse the judgement of the front
wheels and the rear wheels when the vehicle 2 moves backward.
[0102] After the detection of the attaching position of each tire
3, the calculation part 23 can detect the air pressures of the
front left wheel 3a, front right wheel 3b, rear left wheel 3c and
rear right wheel 3d based on the detection signals of the air
pressure sensors 15 of the tires 3 and report them to the user by
screen display with the display part 24 or by sound.
[0103] The following effects are obtained according to this
embodiment.
(1) The user terminal 20 judges the front wheels and the rear
wheels based on data on the direction change of each tire 3
received from each sensor unit 4 and judges the right wheels and
the left wheels based on data of the number of rotations (rotation
speed) of each tire 3 received from each sensor unit 4. Therefore,
as compared with a case where the attaching position of each tire 3
is judged by the intensity of a reception signal from each sensor
unit 4, influence by the intensity of a reception signal from the
sensor unit 4 can be suppressed. (2) Since the attaching position
of each tire 3 is not judged by the intensity of a reception signal
from each sensor unit 4, the distance of the receiving part 21 of
the user terminal 20 from each tire 3 does not need to be
different. Therefore, the degree of arrangement freedom of the user
terminal 20 is enhanced, which is convenient for design. As the
user terminal 20, a portable terminal such as smart phone or tablet
terminal may be used, which is very convenient. (3) Since the
geomagnetic sensor 12 is of a three-axis type and detection axes
are arranged as shown in FIG. 9, even when the geomagnetic sensor
12 is mounted on the inner wall of the rotating tire 3, the
direction of the tire 3 can be advantageously detected without
being influenced by the rotation of the tire 3. (4) Since the
turning direction of the vehicle 2 is detected by the reception
signal of the GPS receiver 22, a GPS receiving function that many
vehicles and portable terminals have can be used, which is very
convenient. (5) Since the detection signals of the distortion
sensor 11 and the geomagnetic sensor 12 of the tire 3 are
transmitted from the transmitting part 15 to the user terminal 20,
when the user terminal 20 is caused to recognize the tire attaching
position, influence by the intensity of the reception signal in the
user terminal 20 can be suppressed. (6) Since the sensor unit 4
transmits the detection signals of the distortion sensor 11 and the
geomagnetic sensor 12 from the transmitting part 15 to the user
terminal 20, when the user terminal 20 is caused to recognize the
attaching position of the tire 3, influence by the intensity of the
reception signal in the user terminal 20 can be suppressed.
[0104] FIG. 14 is a schematic side view showing that distortion
sensors 11a and 11b are arranged at an interval of 180.degree. in
the circumferential direction of the tire 3 and the distortion
sensor 11b is installed at the same position as the geomagnetic
sensor 12 in the circumferential direction of the tire 3. According
to the configuration of FIG. 14, the calculation part 23 of the
user terminal 20 can recognize whether the geomagnetic sensor 12 is
existent on the front half or latter half of the tire 3 from the
output signals (same as those in FIG. 8) of the distortion sensors
11a and 11b. The calculation part 23 can reflect whether the
geomatic sensor 12 is located on the front half or rear half of the
tire 3 on the derivation of the direction of the tire 3 by
inverting the positive/negative sign of the formula 2 every time
the distortion sensors 11a and 11b detect ground contact (every
time changes in the levels of the output signals of the distortion
sensors 11a and 11b are detected).
{square root over (my.sup.2+mz.sup.2)} [formula 2]
[0105] FIG. 15 is a graph showing the relationship between the
detection result of the geomagnetic sensor 12 and the angle .theta.
in view of whether the geomagnetic sensor 12 is located on the
front half or rear half of the tire 3 in the constitution of FIG.
14. It is possible to know the direction change of the tire 3 over
360.degree. by reflecting whether the geomagnetic sensor 12 is
located on the front half or rear half of the tire 3 through
comparison between FIG. 15 and FIG. 11. When the sign of the
formula 2 is inverted every time the distortion sensors 11a and 11b
detect ground contact, the sign of the formula 2 is changed at the
time of the forward movement of the vehicle 2 and at the time of
the backward movement of the vehicle 2. In this point, there is no
problem if it is determined to use the forward movement of the
vehicle 2 for the detection of the attaching position of the tire
3. Even when position detection is carried out at the time of the
backward movement of the vehicle 2, all the tires 3 rotate in the
same direction, thereby limiting influence on position detection.
Or the sign of the formula 2 may be inverted by the calculation
part 23 at the time of backward movement against the time of
forward movement.
[0106] When the distortion sensors 11a and 11b are provided as
shown in FIG. 14, the calculation part 23 can also detect the
half-rotation of the tire 3. Thus, when a plurality of distortion
sensors are mounted in the circumferential direction of the tire 3,
for example, at equal angular intervals, the calculation part 23
can detect less than one rotation of the tire 3.
[0107] While the invention has been described in its preferred
embodiments, it is to be understood by a person having ordinary
skill in the art that variations may be made on each constituent
element and process of the embodiments without departing from the
scope of the following claims. Variations of the invention will be
described hereinafter.
[0108] The distortion sensors 11, 11a and 11b may be each
substituted by an acceleration sensor, or by a ground detection
sensor except for the distortion sensor and acceleration sensor.
The ground detection sensor can detect that a part of the tire 3
which is a part at the same position as the ground detection sensor
in the circumferential direction of the tire 3 contacts the road
surface. The geomagnetic sensor 12 may be substituted by a motion
sensor. The motion sensor can detect the direction change of the
tire 3 as well.
[0109] The number of the tires 3 of the vehicle 2 is not limited to
4 and may be 2, 3 or another arbitrary plural number. The
constituent elements of the sensor unit 4 shown in FIG. 2 are not
integrated into one unit or module and may be independent and
separated from one another. The state data of the tire 3 is not
limited to air pressure data and may be distortion data or electric
property data such as electric capacitance, parasitic resistance or
dielectric loss tangent. The distortion data may be the detection
signal of the distortion sensor 11. The electric capacitance,
parasitic resistance or dielectric loss tangent can be derived from
a result obtained when AC voltage having a predetermined frequency,
for example, 1 kHz to 10 MHz is applied between two electrodes
mounted on the inner wall of the tire 3.
EXPLANATION OF REFERENCE NUMERALS
[0110] 1 tire attaching position detection system, 3 tire, 3a front
left wheel, 3b front right wheel, 3c rear left wheel, 3d rear right
wheel, 4 sensor unit, 5 car body, 7 road surface, 11 distortion
sensor, 12 geomagnetic sensor, 13 air pressure sensor, 15
transmitting part, 21 receiving part, 22 GPS receiver, 23
calculation part, 24 display part, 25 input part
* * * * *